[Amps] preserving tubes

[ian at ifwtech.co.uk]

If a tube has leakage to air, it is doomed anyhow, and storing it in a
vacuum can only delay the inevitable. Leakage will start right in
again when the tube is put into service.

 73 from Ian GM3SEK

----- Original Message -----
From: "David Kirkby" 
To:
Cc:
Sent:Wed, 3 Oct 2012 16:17:59 +0100
Subject:Re: [Amps] preserving tubes

 On 3 October 2012 06:20, Gary Smith  wrote:
 >
 > Is there any benefit to taking a ceramic tube on the shelf and
 > running it every so often and then returning it to the shelf to
 > archive it for a backup when needed? Or os it just as well to let
it
 > sit until needed?
 >
 > Gary
 > KA1J

 I have heard it is worth at least running the heaters up, but I
don't
 know. This is the sort of information Reid Brandon at Eimac could
have
 provided!

 I've often wondered if it is worth storing them in a vacuum - or as
 close to a vacuum as one can reasonably get. There's going to be
less
 diffusion of gases into the tube if the pressure outside is very
low.
 If you stored them at a pressure of 10% of atmospheric (VERY easy to
 achieve), then would it reduce the diffusion by a factor of 10?

 As you try to get to lower and lower pressures, the difficulty
 increases. I don't think you would need to go to the effort of
things
 like diffusion pumps.

 I'll lot you lot think (argue) about that one!

 Dave, G8WRB.
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